The present invention relates to a ball joint, and particularly to a ball joint comprising a socket and ball stud.
2. Description of the Prior Art
Ball joints are known and include a ball stud and socket. The socket has a chamber and an opening. The ball stud has a ball portion located in the chamber and a stud portion extending from the ball portion through the opening. A bearing is disposed between the ball portion of the ball stud and the socket. The ball stud is rotatable about its longitudinal central axis within the socket. The ball stud also pivots or oscillates relative to the socket.
A ball joint is typically used to interconnect relatively movable parts of a steering linkage or a suspension of an automotive vehicle. The ball stud is connected to one part and the socket is connected to another part. The ball stud and socket rotate and oscillate relatively during relative movement of the parts. The ball joint is so constructed that relative movement between the ball stud and socket is resisted. Thus, a predetermined force is required to overcome the resistance to relative movement. The force that is required to overcome the resistance to relative movement is relatively constant.
When the vehicle is moving at a relatively low speed, for example during a parking maneuver, it is desirable to have relatively low resistance to rotative and oscillatory movement of the ball stud and socket. Thus, the force required to overcome the resistance is correspondingly low and the vehicle may be steered with relatively little effort. However, at relatively high vehicle speed, it is desirable that a relatively large resistance to relative rotational movement between the ball stud and socket exists to give a tight or stiff steering "feel" to the operator and to damp wheel vibration that can cause wheel shimmy. It is also desirable to have an increased resistance to relative oscillation or pivotal movement between the ball stud and socket on a smooth road surface to provide a relatively firm support linkage through the ball joint. It is further desirable to have a decreased resistance to relative oscillation on a rough road surface to permit the unsprung mass of the wheel assembly to easily follow the road contour without requiring the sprung mass of the vehicle frame and body to follow the movement of the wheel assembly.